Ultrasound – these are sound waves (acoustic) and are also referred to as supersonic waves. Their frequency is so high that the human ear cannot detect them. The lower limit of ultrasound is considered to be 20 kHz. Sounds above this threshold become inaudible to humans. Conventionally, the upper limit for supersonic waves is 1 GHz. According to this, ultrasound is acoustic waves with a frequency ranging from 20 kHz to 1 GHz. Above this frequency, hypersonic waves appear. Interestingly, ultrasound that is inaudible to humans can be detected or even emitted by some animals, such as dogs, bats, dolphins, rats, or whales.
Ultrasound is used in many aspects of daily life. Based on it, sonars are created for use on surface ships and submarines. Additionally, it is used in medicine, military, cosmetics, food production, and cooking.
Supersonic waves can be produced using various methods, including:
mechanical;
optical;
reverse piezoelectric effect;
thermal;
magnetostriction.
